分段堆场预测调度研究

针对船舶分段移动计划主要依靠人为预测及人工调度的现状,提出BP神经网络来预测一个周期内进出场分段的数量,并研究建立以分段移动度最小为目标的优化模型,模型综合考虑了分段在堆场中的停放位置及进、出场路径。通过分支定界法选择分段在堆场中停放位置的最优方案,并构建启发式规则来确定分段在堆场中的最优进、出场路径,从而实现对模型的求解。以某船厂实际数据为例,对模型在堆场调度问题中的应用进行了实例验证,结果表明,所研究方法可求解得出较优的堆场作业计划,并实现堆场资源的高效利用。     

云计算中基于遗传算法的数据布局策略

数据布局的合理性直接影响数据中心间的数据调度效率,进而提高对用户的数据采集效率。论文以数据中心之间数据调度为基础建立数学模型,利用分布式云计算技术处理用户的海量数据,并提供高性能计算资源和海量存储资源模式。在分布式云计算系统中,数据密集型计算可以有效处理数据中心之间的数据调度,通过遗传算法的全局优化能力产生最佳的近似解,并最终获得数据布局的最佳近似结果。实验结果表明,遗传算法可以有效地计算出最优数据布局的近似结果,并使数据中心之间的数据调度最小化。     

基于树搜索的一种动态空间调度方法

针对大型离散企业产品组装空间调度问题,本文提出了一种基于树搜索的动态调度方法。该方法同时考虑了空间布置和时间调度两方面因素,在整个调度规划周期内,算法分成两部分：一是调度准备阶段,把调度时间分割成连续的时间段,并通过时间约束条件得到在每个分场地内需要组装的模块候选集,同时得到分场地的初始布局状态;二是局部调度阶段,通过深度优先树搜索的方法,在每个时间片内使用局部调度算法进行空间布置搜索,得出最优调度。该方法简单实用,最后,仿真实验说明了所提方法的有效性。     

Object-oriented Analysis with Structured and Integrated Specifications and Solutions (OASISS) for production system control

Tool specification for production system control requires the identification of the main characteristics of the production system. The production systems are varied, and the production control tools (such as scheduling algorithms and resource assignment rules) are often dedicated to only one class of these systems. Tool assessment for production system control requires modelling of the production system. We propose a new approach to production systems, to identify the nature and the complexity of the system according to the classification of Conway et al., and to specify a dynamic model that will allow us to simulate production control decisions. This paper presents this object-oriented approach, which identifies the resources and the organization features of the studied system. It then, proposes some predetermined classes of objects, which enable us to classify the system components and to use pre-existing dynamic models. These dynamic models are based on timed and coloured Petri nets. The overall architecture of our methodology follows three steps: top-down analysis of resources and bottom-up recognition of predetermined objects, instantiation and integration of objects, and implementation of objects. An example illustrates its use in the textile industry.     

Integration of heterogeneous CAD databases using STEP and the Internet

In a large-scale design process, designers cooperate in a complex situation where a variety of software tools run on different hardware platforms. This paper presents a data enhancement approach to integrate heterogeneous Computer-Aided Design (CAD) databases through the Internet. The data enhancement means topological changes in a geometric model and additional information in design semantics. The geometric data is enhanced using a non-manifold modeler to produce data sets valuable in downstream applications such as a Finite Element Method (FEM) solver or a detail design system. As a practical example, a shipbuilding product model database has been implemented based on the Standard for the Exchange of Product (STEP) model data methodology and shipbuilding features. The system has been implemented on a network environment that consists of a Web browser, Common Object Request Broker Architecture (CORBA) objects, a relational database management system, a data enhancement module, and various computer-aided applications.     

基于遍历有向非循环图的实时事务调度算法

移动环境下实时数据库系统负载的不可预测,以及实时事务争夺有限的系统资源经常导致实时事务重启或夭折。传统的实时事务调度算法已不适应,在用有向非循环图表示数据相互间的导出关系的基础上,提出一种基于遍历这种图的实时事务调度算法。结合实时数据对象的时间域和值域有效性,系统适当地丢弃一些低价值的更新事务以减轻系统负载。仿真实验表明：算法一定程度上降低了事务错过截止期比率并提高了数据新鲜度。     

Spatial planning for musical output

This article describes an expert system called ENGRAVE that produces musical notation. This task is a resource allocation problem involving the layout of musical objects in space. to do this, we use a spatial planning technique called constraint guidance to plan the layout of the music. an example is given to illustrate the technique. an additional example is given in another domain to show that constraint guidance has general applicability for spatial planning problems.     

结合物体先验和空域约束的室内空域布局推理

对结构化室内场景的空域布局结构进行估计是计算机视觉领域的研究热点之一.然而,对于内部堆放了众多杂乱物体的室内场景,现有的大多数方法容易受到各种物体遮挡的影响而无法对这一类场景的布局结构进行准确推理.为此,本文方法充分考虑了房间和物体之间的几何和语义关联性,参数化地对房间和内部物体的三维体积分别进行描述,并且提出利用多种高层图像语义来获取物体的先验信息.此外,还在此基础上加入了空域排他性和空域位置等多种空域约束,进而在改进室内场景空域布局估计的同时为物体的识别和定位提供关键信息.本文方法不仅具有较低的求解复杂度,而且通过试验表明相比于现有的经典方法在杂乱的室内场景中能够取得更为鲁棒的空域布局推理结果.     

SIG框架基于多线程技术分布式系统的任务调度

空间信息网格是利用网格技术实现空间信息资源的共享、管理和提供空间信息服务的系统和各种的空问信息服务的基础设施,任务调度是分布式系统和网格系统最具有挑战的问题之一,Java语言里的多线程机制很好地解决了这一问题。该文主要研究了SIG中的任务调度技术,通过实验确定分布式系统里的线程数目,使系统性能获得局部最优。     

On Task Scheduling Accuracy: Evaluation Methodology and Results

Many heuristics based on the directed acyclic graph (DAG) have been proposed for the static scheduling problem. Most of these algorithms apply a simple model of the target system that assumes fully connected processors, a dedicated communication sub-system and no contention for the communication resources. Only a few algorithms consider the network topology and the contention for the communication resources. This article evaluates the accuracy of task scheduling algorithms and thus the appropriateness of the applied models. An evaluation methodology is proposed and applied to a representative set of scheduling algorithms. The obtained results show a significant inaccuracy of the produced schedules. Analyzing these results is important for the development of more appropriate models and more accurate scheduling algorithms.     

手机动画空间布局规划的设计与实现

手机3D 动画自动生成系统是要实现从用户发送信息给服务器,经过信息抽取、情节规划、场景规划等一系列的处理,最终生成与短信内容相关的视频动画并发送给接收方这一过程。其中场景规划模块是在情节定性规划的基础上确定情节的各个细节,并将其量化到三维动画场景文件中。在动画情节规划的基础上,对动画场景规划模块中的三维场景空间布局问题进行研究,将三维场景可用空间根据物体的语义信息进行布局,基于语义网技术设计和实现三维场景的布局知识库,最终实现了三维物体的合理摆放,系统不仅保证了物体的无遮挡、无碰撞摆放,也实现了同一物体添加多个的情况,使物体的摆放具有多样性同时也体现了物体的语义信息。     

Using augmented reality to build digital twin for reconfigurable additive manufacturing system

The extrusion-based additive manufacturing (AM) processes are those where one or multiple tools (usually nozzles) are driven along predefined paths to deposit fabrication materials. They are usually inherently slow because solid contours have to be filled with mere single deposition lines of material. An intuitive way to improve the fabrication speed is to introduce multiple independent actuators for concurrent deposition of materials without collision among them. In this paper, a methodology of using augmented reality (AR) technique is presented to conveniently communicate the layout information between a reconfigurable AM system made of robotic arms and its corresponding digital twin for toolpath planning and simulation. A prototype system made of two desktops AM robotic arms is developed, and transformation matrices are derived to determine the spatial relation between different items in the system, including camera, markers, robotic arms and part substrate. Case studies are conducted to demonstrate the capability of this methodology in automatically retrieving layout information and assisting users to deploy pre-determined layout. The results show that the developed methodology enables rapid retrieval of position information from the physical system layout into the digital twin simulation and optimization and facilitates convenient deployment of an optimized layout determined in the digital twin into the physical system.     

Real-time interactive MPEG-4 system encoder using a cluster ofworkstations

MPEG-4 currently being finalized by the Moving Pictures Experts Group of the ISO is a multimedia standard, MPEG-4 aims to support content-based coding of audio, text, image, and video (synthetic and natural) data, multiplexing of coded data, as well as composition and representation of audiovisual scenes. One of the most critical components of an MPEG-4 environment is the system encoder. An MPEG-4 scene may contain several audio and video objects, images, and text, each of which must be encoded individually and then multiplexed to form the system bitstream. Due to its flexible features, object-based nature, and provision for user interaction, MPEG-4 encoder is highly suitable for a software-based implementation. A full-scale software-based MPEG-J system encoder with real-time encoding speed is a nontrivial task and requires massive computation. We have built such an encoder using a cluster of workstations collectively working as a virtual parallel machine. Parallel processing of MPEG-4 encoder needs to be carried out carefully as objects may appear or disappear dynamically in a scene. In addition, objects may be synchronized with each other. User interactions may also prohibit a straightforward parallelization. We propose a modeling methodology that captures the spatio-temporal relationship between various objects and user interaction. We then propose a number of scheduling algorithms that periodically allocate MPEG-4 objects to multiple workstations ensuring load balancing and synchronization requirements among multiple objects. Each scheduling algorithm has its own performance and complexity characteristics. The experimental results, while showing real-time encoding rates, exhibit tradeoffs between load balancing, scheduling overhead cost, and global performance     

嵌入式浏览器解析排版并行化研究与设计

提出一种嵌入式浏览器网页解析与排版的并行化处理方法。通过将嵌入式浏览器控制和排版划分为主线程，资源加载和解析划分为从线程，将串行的网页解析和排版过程并行化，并根据浏览器消息类型进行调度管理。结合操作系统的线程调度模式，该方法克服了单页面解析、排版的单线程响应效率差而造成用户体验较差的问题。经实例测试，验证了该方法的可行性，并且在内存消耗不超过64MB的情况下，首屏显示速度提高了4%~17%。     

Shop-floor scheduling at shipbuilding yards using the multiple intelligent agent system

The intelligent agent system has become a typical approach to research distributed artificial intelligence and distributed problem solving. However, despite its various technical advantages, the distribution and expansion of the intelligent agent system approach has been limited because existing methodologies rely on specialized applications and therefore require intensive investment to develop new systems. In an attempt to conquer these difficulties, a standardized methodology to construct intelligent agent systems is proposed. This approach deviates from current agent system approaches of repeatedly constructing new and customized expert systems. Specifically, it provides an economical method for developing intelligent agent systems by investigating the possibility of standardizing message communication protocols in linguistics speech-act theory and by supplementing traditional algorithmic systems with intelligent segments using, among others, expert system tools. To verify effectiveness, the shop-floor scheduling system of a large-scale shipbuilding yard has been redesigned, developed, and tested using this approach. This shop-floor scheduling system requires the scheduling of when and where to process block construction under various constraints. It is a difficult four-dimensional time and space allocation problem involving traditional NP-complete search spaces. The tested intelligent agent system proposes an innovative method for reducing the search space into three levels: the algorithm level, the agent intelligence level, and the level of cooperation among agents. It also provides methods for solving deadlock occurrence and non-uniformity problems resulting from parallel processing. Test results demonstrate applicability and economy, among other technical advantages.     

造船监理员调度模型和混合遗传算法求解

有效快速地调度不同专业的造船监理员至不同厂区进行监理工作可以提高船舶建造效率,确保船只建造质量。针对我国造船监理公司监理员调度方面缺乏通用模型和调度手段落后的问题,建立起带有一系列硬性约束和软性约束的数学模型。随后针对该数学模型采用了基于模拟退火遗传算法的混合遗传算法进行求解。模拟仿真实验表明该模型与算法取得了理想效果。     

Resource management using multiple feedback loops in soft real-time distributed object systems

This paper describes a Resource Management System for a soft real-time distributed object system that is based on a three-level feedback loop. The Resource Management System employs a profiling algorithm that monitors the usage of the resources, a least laxity scheduling algorithm that schedules the methods of the tasks, and hot spot and cooling algorithms that allocate and migrate objects to balance the loads on the resources. The Resource Management System consists of a single Resource Manager for the distributed system, and a Profiler and a Scheduler located on each of the processors in the distributed system.     

Distributed manufacturing control with extended CNP interaction of intelligent products

This paper describes two heterarchical architectures which use distributed intelligence for the control (operation scheduling, resource allocation and product routing) of a manufacturing cell. In these architectures intelligence is put respectively at the product and through the network of workstation computers. The cost of embedded specialized hardware required for the first option is still very high. The second option needs the utilization of Automatic Identification and Data Capture technology close to the product to permit its identification and tracking by the computer system. These technologies enable the automated identification of objects, the collection of data about them, and the storage of that data directly into computer systems. Through this network, the computer system can access or update information in databases about the products and connect with software agents that represent production orders and resources and take in common decisions through negotiation and contract-based rules. The theory of the proposed solutions is based on the holonic manufacturing and product-driven automation concepts. The implementation methodology along with experimental results is presented, emphasizing the advantages of each solution.     

时空模型及时空运行图

周期性实时系统已被广泛研究,与之相关的自动调度算法主要有三类:优先级驱动的犤1,4,5,7犦、基于速率的犤2,3犦和基于时间的犤8,9犦。这些自动算法虽然能解决许多应用问题,但有时得出的调度方案不一定是最佳的;有时甚至干脆得不出要在整个运行期间均满足要求的调度方案,如某些临界区的存取就可能导致EDF(EarliestDeadlineFirst)犤7犦算法无解。主要原因是单一的算法难以保证适应各种复杂的应用环境。论文从系统的资源划分出发,提出了时空模型及时空运行图的概念,阐述了利用时空图来调整已得调度方案的理由,并通过举例,说明应用时空图确实可能优化自动算法得出的调度方案。     

多回路网络化控制系统级联反馈调度

针对动态环境下的多回路网络化控制系统，本文基于反馈控制与网络调度协同设计的思想，提出一种级联反馈调度策略．以优化系统整体控制性能为目标，根据可用带宽资源的动态变化，对控制回路采样周期进行在线调节，将截止期错过率控制在期望的较低水平，并对可用带宽进行优化分配．仿真实验结果表明，相对于传统设计方法，该方法能够明显改善整体控制性能．